Computerization, digitalization and datafication are by far no neutral or self-dependent occurrences. They are, to a large degree, co-determined by heterogeneous actors who reflect about, construct, configure, manipulate or even control media. The contributors to this issue put the spotlight on these actors and investigate how they influence, shape and (re)configure broader social constellations. Instead of exploring what people do with media, the articles focus on the many ways individuals, civil society initiatives, corporations and social movements act on media. The notion of acting on media denotes the efforts of a wide range of actors to take an active part in the molding of media organizations, infrastructures and technologies that are part of the fabric of everyday life. Therefore, by conceptualizing acting on media as a form of political action, the issue aims to contribute to ongoing discussions on the media practice paradigm.